The process of this invention concerns the replacement of a halogen atom or an aromatic substrate by the alkyl or aryl moiety of a Grignard or zinc reagent. The reaction is catalyzed by a nickel/tridentate phosphorus catalyst complex, or a nickel/bidentate phosphorus catalyst complex in the presence of added triarylphosphine.
The selective cross-coupling of Grignard reagents with aryl halides is known: Corriu et al., JCS Chem. Comm., 144 (1972); Tamao et al., J. Am. Chem. Soc., 94, pages 4374 to 4376 (1972). In the latter publication, the reaction is catalyzed by a nickel-bidentate phosphine complex and the dihalo substrates give almost exclusively dialkyl products. A similar Grignard reaction: Yamamura et al., J. Organometal. Chem., 91, C39 to C42 (1975), is catalyzed by a palladium-bidentate phosphine complex to give primarily dialkyl products.
Tamao et al., Bull. Chem. Soc. Japan, 49, pages 1958 to 1969, (1976) report that bidentate phosphine-nickel complexes give higher catalytic activity for the reaction of aryl halides with Grignard reagents. Dihaloaromatics are shown to ordinarily give dialkyl aromatic products. It is noted at page 1964 that "dichlorobenzenes are smoothly dialkylated even in the presence of two-fold excess of dichlorobenzene over the alkyl Grignard reagent". An Example at page 1963, Table 7, line 11, describes monoalkylation of a particular dihaloaromatic compound under reaction conditions different from those described herein.
Minato et al., in Tetrahedron Lett., 21, pages 845 to 848 (1980), note that use of a palladium-monodentate or bidentate phosphine complex allows selective formation of monoalkylated products from dibromoaromatics.
Friedel-Crafts replacement reactions usually work poorly with dihalide-containing reactants and are often subject to alkyl rearrangement. In addition, halide replacement by an aryl substituent rarely works in Friedel-Crafts type reactions. Lithium alkylations and arylations of compounds containing dihalide substitution generally tend to give dialkylations and diarylations and are characterized by poor selectivities. See, in this regard, March, "Advanced Organic Chemistry", McGraw-Hill, N.Y., 1968, page 509. Other alkylation reactions are reviewed by Coffey, Ed., in "Rodd's Chemistry of Carbon Compounds", 2nd edition, Vol. IIIA, Elsevier, NY, 1971, pages 241 to 287.
Negishi, Acc. Chem. Res., 15, 340 to 348 (1982) reviews the use of both Grignard and zinc reagents in selective crosscoupling reactions and notes the following arylzinc/aryl iodide reaction: ##STR1## (Larson, et al., Tetrahedron Lett., 5041 (1979)).
The characteristics by which the process of this invention differs from the various methods of the prior art as represented by the foregoing citations includes, in combination: selective formation of monoalkylated and/or monoarylated products from dihaloaromatic starting reactants in good yield after relatively short reaction times employing easy to use nickel/bidentate or tridentate phosphorus complex catalysts. Certain of said catalysts are described by King et al., in Inorg. Chem., 10, pages 1841 to 1850 (1971).